Portable information terminal apparatus, voltage measurement apparatus, voltage measurement method and program thereof

Abstract

The measurement unit measures a voltage by converting it from analog to digital and outputs a measurement value. The changeover unit, being connected to a battery and a reference voltage source generating a highly accurate fixed voltage, selects one of them and applies it to the measurement unit. The voltage value output unit makes the changeover unit select a fixed voltage generated by a predetermined voltage source, makes the measurement unit measure it as a reference voltage and generates calculation-use information for calculating a voltage value from a measurement result based on a measurement value of the fixed voltage and a voltage value of the reference voltage. The voltage value output unit, when making the changeover unit select a voltage of the battery and making the measurement unit measure it, uses the measurement value of it and the calculation-use information to calculate and output a voltage value of the battery.

Description

BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] The present invention relates to a portable information terminal apparatus such as a portable telephone, a PDA (Personal Digital Assistance), an HHT (Hand Held Terminal), a lap top PC (Personal Computer), and a voltage measurement apparatus installed therein; and in particular to a technique aiming at measuring a voltage value of a power supply-use battery with maintaining accuracy. [0003] 2. Description of the Related Art [0004] A portable information terminal apparatus (simply “portable information terminal” hereinafter) is usually configured to be operable by a rechargeable battery. A capacity of the battery equipped on the portable information terminal is limited. Accordingly the majority of portable information terminals is equipped with the function (called a “battery monitor function” hereinafter) of displaying a remaining battery capacity or issuing a warning when the voltage value becomes no more than a cer...

AI Technical Summary

Benefits of technology

[0012] The purpose of the present invention is to provide a technique allowing a voltage measurement with maintaining high accuracy and without requiring an operator for a cumbersome operation.

[0014] The present invention utilizes a voltage source which generates a known stable voltage (i.e., a fixed voltage) by using an electric current supplied from a battery and uses the fixed voltage for creating calculation-use information for calculating a voltage value matching with a measurement accuracy of the measurement unit. A creation of the calculation-use information enables the measurement unit adequately respond, including a state of being equipped on a portable information terminal apparatus. It enables a measurement of a value of a battery voltage to maintain accuracy regardless of a variation of measurement accuracy for each of the measurement units or a variation of a resistor connected to the measurement unit. This also makes it easy to validate for the purpose of rejecting a measurement unit whose measurement error is outside a tolerance range during a production process of an apparatus equipped with a voltage measurement apparatus according to the present invention or of a portable information terminal apparatus according thereto.

Problems solved by technology

A capacity of the battery equipped on the portable information terminal is limited.

Due to this, work efficiency is low, that is, a cumbersome operation is necessary for a high accuracy measurement.

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